In response to a recent column on keeping raccoons out of your garden, I received an email from Carolyn Arthur, a customer service specialist at Sperling Nursery in Calabasas.  “What about grubs?,” she wrote.  “They are the likely reason that people have raccoons.  Grubs seem to be omnipresent in yards these days.”

The grubs to which Arthur refers are larvae of scarab or dung beetles.  Yes, they are those same beetles that were worshipped in ancient Egypt and appear on the tombs of Pharaoh and his family members.  Scarab grubs are most active during the fall and are most often found in lawns.  The particular type that cause havoc in Southern California are masked chafer grubs.  Their depradations result in dead spots in the lawn, even where irrigation is adequate. Raccoons, coyotes, skunks, and crows are all attracted to lawns that are grub enriched.  The damage they cause is most visible at this time of the year.

Warm season or tropical grasses such as Bermuda and Kikuyu are more likely to harbor grubs than cool season grasses such as fescue, ryegrass, and bluegrass.  However, cool season lawns are more likely to show grub damage.  Grubs feel most at home in the thatch which builds up in both warm season and cool season grasses, even if warm season thatch is more apparent to the naked eye.  One product that quickly controls grubs is “Bayer 24 hours Grub Killer plus.”  According to the label, it “works on contact, delivers overnight results.”

You may be able to eschew chemical control with the help of spike sandals.  Spike sandals are advertised as footgear for aerating lawns.  You can quickly locate them via an Internet search.  You wear these sandals while traipsing across your lawn.  Unfortunately, they have never really been effective in aerating lawns, a task for which gas-powered equipment is required.  However, Colorado State University research demonstrated that 3-5 treks across a lawn in spike sandals can reduce grub population by 50%.  A grub only needs to be nicked by a spike for it to meet its eternal reward.  Prior to walking, you will need to soak your lawn in order to draw grubs to the surface.  ¼ to ½ inch of water should be applied before donning your spike sandals.  The soil under lawns is typically compacted and can absorb only 0.2 inches of water per hour.  Conventional spray sprinklers apply 0.2 inches of water in approximately 5 minutes so you will need to water for 5 minutes, wait an hour, water for 5 minutes again, wait another hour, and water for a third 5 minute interval to make sure you have applied the proper amount of water.  If you have slow moving rotary sprinklers, which apply water 3 times slower than conventional sprinklers, you will need to water for 15 minutes, instead of 5 minutes, three times, with an hour between each application.

You may also opt for biological control of lawn grubs.  This is effectively achieved through the use of a nematode species (Heterorhabditis bacteriophora), an unsegmented worm that parasitizes and liquefies scarab grubs.  An Internet search will reveal vendors who supply beneficial nematodes.  A search of “biological control” will bring up companies that specialize in pest control of this type, where one type of living organism preys on another.  Incidentally, the same nematodes that prey on grubs will also parasitize ants, fleas, moths, and flies.

Nematodes are easily applied. They arrive in a powdery clay compound that you mix with water.  You can then water it in with a watering can, hose end applicator, or pump sprayer.  Nematodes are most effective when applied during the cooler times of the day, whether late morning or early afternoon.  Grubs are killed within 48 hours of contact with parasitic nematodes. You can store nematodes in a refrigerator for two weeks.

Speaking of lawns, they are not all bad.  Regarding the subject of firescaping – landscaping that reduces the threat of a wildfire engulfing your home – lawns are highly recommended.  A large swath of lawn surrounding a wilderness home is a good idea.  If a fire is in the vicinity, activation of lawn sprinklers will provide a hydrated buffer to an encroaching inferno.  And, in a worst case scenario, if your house should catch fire, a lawn provides the optimal staging area for fire fighting trucks and equipment.  A fancy landscape with boulders and elaborate hardscape features will do nothing but keep firefighters and their trucks at a distance.

Peggy Brutsche, from Long Beach, applauded a column that described a drought tolerant garden but lamented the fact that I did not mention California natives as alternatives or complimentary plants to firethorn (Pyracantha spp.) and lavender.  Brutsche wrote that “Pyracantha is considered invasive here . . . (and) many California natives – buckwheats (Eriogonum spp.), sages (Salvia spp.), manzanitas (Arctostaphylos spp.), and others – are as sturdy as French lavender (Lavandula dentata), and mix well with it in the garden.  Good replacements for Pyracantha include toyon (Heteromeles arbutifolia), with its white flowers and red berries, and similar shrubs/trees like coffeeberry (Rhamnus californica) and lemonade berry (Rhus integrifolia). . . Native plants also have the advantage of attracting native birds, butterflies, and other pollinators, who are needed to maintain the diversity and health of our California habitat.”

Tip of the Week:  Outside of Handy J Car Wash in Sherman Oaks, on Moorpark Street, you will find a thriving crop of sugarcane (Saccharum officinarum).  Sugarcane is easy to propagate and grow.  You cut off a segment from an existing plant, stick it in the gound, and it establishes roots of its own.  Sugarcane makes an appetizing snack.  Its canes can be chopped into small, woody pieces which, when sucked, are sweetly refreshing.